CMOS图像传感器光子转移曲线辐照后的退化机理

Degradation mechanism for photon transfer curve of CMOS image sensor after irradiation

针对EMVA 1288标准测试辐照后互补金属氧化物半导体(CMOS)图像传感器的重要性能参数(光子转移曲线和转换增益)适用范围受限的问题,提出了针对辐照后CMOS图像传感器光子转移曲线和转换增益的改进的测试方法。该方法通过调整测试条件,限制辐照后CMOS图像传感器的暗电流和暗电流非均匀性噪声,求解出辐照后正确的器件性能参数,从而直观地得知辐照所引起的器件性能变化。利用该方法进行了实验测试,结果显示:辐照导致转换增益比辐照前退化了7.82%。依据此结果分析了辐照导致光子转移曲线和转换增益退化的机理,认为转换增益的退化是由于质子辐射引起的电离效应和位移效应导致暗电流、暗电流非均匀性增大所致。本文为掌握CMOS图像传感器的空间辐射效应提供了理论基础。

As application scopes of photon transfer curve and conversion gain of a CMOS（Complementary Metal-oxide-Semiconductor）image sensor are limited after irradiated by EMVA 1288 standard testing,an improved testing method of photon transfer curve and conversion gain of CMOS image sensor is presented.By adjusting test conditions,the method limits the dark current and the non-uniform noise of dark current from the CMOS image sensor after irradiation to solve the correct device parameters.By which the device performance changes caused by irradiation are intuitively obtained.An experimental test is performed with the proposed method,and the results show that the switching gain caused by irradiation is reduced by 7.82%.On the basis of the results,the degradation mechanism of photon transfer curve and conversion gain of the CMOS caused by irradiation is analyzed.The results point out that conversion gain degradation comes from the increses of dark current and the non-uni-form noise of dark current caused by the proton radiation ionization effect and displacement effect.The paper provides a theoretical basis for mastering the spatial radiation effect of CMOS image sensors.